Optical grinding and polishing machine



July 21, 1964 J. P. CHARLTON OPTICAL. GRINDING AND POLISHING MACHINE 7Sheets-Sheet 1 Filed Dec. 7, 1962 WrM Q a 8. BY ME w 5 3 a M 52 ).4 Wm vkww ww July 21, 1964 .1. P. CHARLTON OPTICAL. GRINDING AND POLISHINGMACHINE 7 Sheets-Sheet 2 Filed Dec. '7. 1962 INVENTOR. JAMES P CHARLTONA TTOENEYS July 21, 1964 J. P. CHARLTON 3,141,265 OPTICAL GRINDING ANDPOLISHING MACHINE Filed Dec. 7, 1962 7 Sheets-Sheet 3 W INVENTOR. 1JZIMES P ARLTON July 21, 1964 J. P. CHARLTON OPTICAL. GRINDING ANDPOLISHING MACHINE Filed Dec. 7, 1962 7 Sheets-Sheet 4 .WP A 6 NW mr p Slllllg l H July 21, 1964 J. P. CHARLTON 3,141,265

OPTICAL GRINDING AND POLISHING MACHINE Filed Dec. 7, 1962 '7Sheets-Sheet 5 IN VEN TOR.

J'AMss P. CHAIPLT'O/V July 21, 1964 .1. P. CHARLTON OPTICAL GRINDING ANDPOLISHING MACHINE 7 Sheets-Sheet *6 Filed Dec. 7, 1962 INVENTORL JZIMESx CHARLTON A 7- roe/ve Y5 July 21, 1964 J. P. CHARLTON OPTICAL GRINDINGAND POLISHING MACHINE '7 Sheets-Sheet 7 Filed Dec. 7, 1962 INVEN TOR.

m M 0 U9 2 #A M C P JAMES BY %%ma, fl

United States Patent 3,141,265 ()PTICAL GRINDING AND POLISHWG MACHHNEJames 1. Charlton, R0. Box 95, Diliwyn, Va. Filed Dec. 7, 1%2, Ser. No.242fi53 13 Claims. (Cl. 5126) This invention relates to grinding andpolishing machines for forming high precision optical surfaces, and moreparticularly to an optical grinding and polishing machine wherein anoptical blank is moved over a rotating abrading die in a predeterminedpath of movement.

A main object of the invention is to provide a novel and improvedgrinding and polishing machine of the type in which an upper opticalblank is supported in engagement with a rotating second optical blank,with a layer of suitable abrasive material interposed therebetween sothat the adjacent surfaces of the blanks are formed in accordance withone another, with the thickness of the abrasive layer, and with theamount of energy spent in removing material from the blanks, the machinebeing provided with means for rotating the upper blank andsimultaneously moving it in a predetermined path, the movement of saidupper blank being accomplished by means of amplitude-modulated strokesin a plane perpendicular to the axis of rotation of the lower blank andwherein the path of movement of the axis of the upper blank hassubstantially a closed loop configuration.

A further object of the invention is to provide an improved opticalgrinding and polishing machine of the type wherein an upper opticalblank is supported with its bottom surface in abrasive contact with thetop surface of a rotating lower blank, the machine being arranged tomove the upper blank substantially horizontally while rotating same witha movement whose path is the resultant of horizontal reciprocation ofsaid upper blank and simultaneous lateral movement thereof in adirection substantially perpendicular to the direction of its horizontalreciprocation.

A still further object of the invention is to provide an improvedoptical grinding and polishing machine of the type employing acontinuously rotating horizontal lower optical blank which rotates on astationary vertical axis and means to support an upper rotating opticalblank against the top surface of the lower blank, with suitable abrasivematerial interposed between the blanks, with means to simultaneouslyreciprocate the upper blank horizontally in one direction and toreciprocate it laterally in a direction substantially perpendicular tothe firstnamed direction of horizontal reciprocation, whereby tomodulate the movement of the upper blank in a manner to provide maximumuniformity of the abrading action on the adjacent surfaces of theblanks, the machine being provided with easily operated means to adjustthe elements which define the various parameters of the figure ofmovement of the upper blank.

A still further object of the invention is to provide an improvedoptical grinding and polishing machine of the type employing a rotatinglower blank which revolves on a fixed vertical axis and means to supporta rotating upper blank in abrasive contact therewith and to move theupper blank horizontally in a predetermined geometrical pattern so as toproduce a relatively high degree of uniformity of abrasive action on theadjacent surfaces of the blanks, the machine being relatively compact insize, being reliable in operation, being durable in construction, andbeing easy to adjust.

Further objects and advantages of the invention will become apparentfrom the following description and claims, an from the accompanyingdrawings, wherein:

FIGURE 1 is a top plan view of an improved optical 3,141,265 PatentedJuly 21, 1964 grinding and polishing machine constructed in accordancewith the present invention.

FIGURE 2 is a side elevational view of the machine illustrated in FIGURE1.

FIGURE 3 is a transverse vertical cross sectional View takensubstantially on the line 33 of FIGURE 2.

FIGURE 4 is an enlarged horizontal cross sectional view takensubstantially on the line 4-4 of FIGURE 2.

FIGURE 5 is a longitudinal vertical cross sectional view takensubstantially on the line 5-5 of FIGURE 1, and drawn to a substantiallyenlarged scale.

FIGURE 6 is a horizontal cross sectional view taken substantially on theline 66 of FIGURE 2.

FIGURE 7 is a horizontal cross sectional view similar to FIGURE 6, butshowing the parts at a diiferent portion of the operating cycle of themachine.

FIGURE 8 is an elevational detail view, partly in cross section, of themain drive crank frame of the machine of FIGURES 1 to 7, and the partsimmediately adjacent thereto.

FIGURE 9 is a horizontal cross sectional view taken substantially on theline 9--9 of FIGURE 8.

FIGURE 10 is a side elevational view, similar to FIG- URE 8, and partlyin cross section, showing the parts in a somewhat different position inthe cycle of operation of the machine.

FIGURE 11 is a horizontal cross sectional view taken substantially onthe line 1111 of FIGURE 10.

FIGURE 12 is a vertical cross sectional View taken through the upperoptical blank, and illustrating the manner in which the upper opticalblank moves over the forming surface of the subjacent optical blank, forexample, from the position thereof shown in FIGURE 7 to the positionthereof shown in FIGURE 6.

FIGURE 13 is a fragmentary transverse vertical cross sectional view,taken substantially on the line 13-13 of FIGURE 5.

FIGURE 14A is a diagram illustrating the two paths of movement of theaxis of the upper blank in two different positions of adjustment of ahorizontal crank rod of the oscillating mechanism for the upper blanksupporting angle bars of the machine of FIGURES 1 to 13.

FIGURE 14B is a diagram illustrating the two paths of movement of theaxis of the upper blank, with the crank rod adjustments of FIGURE 14Abut with the vertical pivot axis of the angle bars in a differentposition of adjustment.

FIGURE 14C is a diagram illustrating the two paths of movement of theaxis of the upper blank, with the crank rod adjustments of FIGURE 14A,but with the vertical pivot axis of the angle bars in a furtherdifferent position of adjustment.

Referring to the drawings, 14 generally designates an improved opticalgrinding and polishing machine according to the present invention. Themachine 14 comprises a base 15 on which is mounted a supporting frame 16provided at one end with a pair of vertically spaced bearing brackets17, 17 in which is supportingly journaled a vertical shaft 18 on the topend of which is secured a circular tray 19. Secured to the shaft 18immediately subjacent the tray 19 is a drive pulley 20. Secured in thecentral portion of the tray coaxially with the shaft 18 is a block 21provided with upstanding pins 22 defining an enclosure receiving a lowerblank 23, concentrically secured on a spherically rounded bottomsupporting disc 69, which is thus coaxially supported on the block 20for rotation therewith.

As shown in FIGURE 1, the block 21 is substantially square in shape, theupstanding pins 22 being located at the corner portions of the block,and the circular lower blank 23 being received inside the pins, the pinsengaging the periphery of the circular blank 23 so as to keep itcentered relative to block 21 and the axis of rotation of the assemblycomprising shaft 18 and tray 19. Spacing blocks 24 are interposedbetween the lower blank 23 and the supporting block 21, to define aspace therebetween for the free passage of liquid containing abrasivematerial, said passage communicating with a central bore 25 provided inthe supporting block 21, said bore 25 receiving the depending universaljoint connection bracket 70 of disc 69 and communicating with radialpassages 26 provided at the bottom of the supporting block 21, saidradial passages being in communication with the outer portions of tray19. An annular drain trough 27 is supported by frame 16, for example, bya bracket 28' secured on said frame, the drain trough 27 surroundingshaft 18 'and being located beneath drain apertures 28 provided in thecentral portion of tray 19. Connected to the peripheral portion of theannular drain trough 27 is a drain conduit 29 leading to a suitablereceiving container.

Designated at 30 is an electric motor which is vertically mounted in theframe 16 and which has an output shaft coupled through a transmissionunit 31 to a cone pulley 32. Cone pulley 32 is drivingly coupled to avertically mounted cone pulley 33 which is secured on a vertical shaft34 journaled in the top portion of frame 16, a pair of relatively smallpulleys 35, 35 being secured to the top portion of shaft 34, adjacent toeach other, as shown in FIGURE 3.

Cone pulley 32 is drivingly coupled to cone pulley 33 by a belt 36.Designated at 37 is a vertical shaft which is rotatably supported in avertical sleeve 38 and a bottom bearing bracket 39 secured to the end offrame 16 opposite the shaft 18, as shown in FIGURE 2. Secured on theupper portion of shaft 37 are a pair of relatively large pulleys 40, 40which are drivingly coupled to the pulleys 35, 35 by respective drivebelts 41, 41. A cone pulley 42 is secured on shaft 37 below the pulleys40, 40. Cone pulley 42 is drivingly coupled by a belt 43 to a conepulley 44 secured on a vertical shaft 45 journaled in the top portion offrame 16. Cone pulley 44 is drivingly coupled to the large drive pulley20 associated with the tray 19 by a belt 46.

I It will be thus readily apparent that the motor 30 simultaneouslydrives the tray 19 and the vertical shaft 37.

Rigidly secured to the top end of the shaft 37 is a horizontal arm 47 ofinverted V-shaped cross section. Designated generally at 48 is a crankframe comprising a bottom horizontal arm 49 of V-shaped cross sectionwhich is slidably received in the arm 47 and which is clampingly securedthereto in adjusted position relative to the vertical shaft 37 by aclamping assembly 50.

The clamping assembly 50 comprises an outer sleeve member which slidablyembraces the nested members 47 and 49, being provided with top clampingflanges 51, 51, and being provided with a bottom vertical clamping screw52 which is threadedly engaged through the bottom corner of the clampingsleeve 50 and which is clampingly engageable with the bottom corner of aV-shaped clamping plate 53 which is disposed subjacent the arm 47, theV-shaped clamping plate 53 being received in the generally V-shapedbottom portion of the clamping member 50, and the top edges of themember 53 being clampingly engageable against the respective walls ofthe inverted V-shaped member 47.

Vertical angle bars 54, 55 are rigidly secured to the opposite ends ofthe arm 49, a transverse angle bar 56 being secured to the top end ofthe .bar 55. Respective horizontal angle bars 57, 57 are rigidly securedto the opposite end portions of the transverse angle bar 56, the anglebars 57, 57 extending parallel to the bottom arm 49 and being secured atthe ends thereof opposite the angle bar. 56 to the top portion of theangle bar 54.

The angle bars 57, 57 are arranged with their vertical flanges disposedinwardly, defining a guide slot extending longitudinally of the frame48. Slidably supported on the parallel angle bars 57, 57 are a pair ofparallel angle bars 58, 58 between the intermediate portions of which iswelded a vertical upstanding bearing sleeve 59 through which rotatablyextends a vertical shaft 60. Rigidly secured to the bottom end of theshaft 68 is an upwardly facing horizontal V-shaped arm 61 to which isadjustably secured a pivot bracket 62, the bracket 62 being generallyV-shaped and nestingly receiving the arm 61 and being provided withmeans to clamp same to the arm 61 at an adjusted position along thelength of said arm. The bracket member 62 is provided with the dependingpivot ball 63 which is received in a ball socket provided in a pivotbearing member 64 which is adjustably mounted on a horizontal rod 65pivotally connected to the bottom arm 49. Thus, the arm 49 has rigidlysecured thereto a vertical upstanding pivot shaft 66 on which isrotatably engaged a vertical bearing sleeve 67 which is rigidly securedto the end of the rod 65.

As will be apparent from FIGURE 5, the vertical drive shaft 37 rotatesthe frame 48 around the axis of shaft 37, whereby the vertical pivotshaft 66 moves in a circular path concentric with the axis of shaft 37.Since the entire frame 48 rotates, the vertical shaft 60 is constrainedto rotate with the frame, namely, to describe a circular path, but isalso reciprocated longitudinally of the frame due to the linkage,comprising arm 61 and rod 65, connecting shaft 60 to the rotating arm49. Thus, the pivot point defined by the ball 63 rotates and oscillatesas the vertical shaft 66 moves in the aforesaid circular path, causingthe parallel angle bars 58 to slide back and forth along the bars 57,meanwhile rotating with the frame 48. The resultant of the combinedcircular and reciprocating movements of the shaft 60 is a rotatingvarying substantially closed-loop path such as 60a or 6012 in FIGURES14A, 14B or 140, whose parameters vary with time and are determined bythe effective radius of the circular path of shaft 66, the elfectivelength of the links defined by the rod 65, namely, the distance betweenshaft 66 and the adjustable pivot bracket 64, and the length of the linkdefined between the axis of shaft 60 and the pivot ball 63, namely,defined by the adjustment of the member 62 on the arm 61.

The upper optical blank, shown at 68, is cemented to a supporting disc69 which is rotatably connected, by a universal joint 70, to a verticalshaft 71 to the top portion of which is secured a pulley 72. A verticalsleeve 73 rotatably receives the shaft 71, said sleeve 73 being rigidlysecured between the ends of a pair of angle bars 74, 74 which extendhorizontally, substantially parallel to each other. A vertical sleeve 75is pivotally secured between the opposite end portions of the angle bars74, 74, said sleeve 75 rotatably receiving the vertical sleeve 59. Theangle bars 74, 74 are transversely connected by fastening bolts 76 atspaced points therealong.

Adjustably secured, as by a clamping bracket 77, to an upstandingvertical post 78 provided on frame 16 is a horizontal inwardly extendingrod 79 which is provided at its inner end with an upstanding verticalshaft portion 80 extending between the angle bars 74, 74, said shaftportion being rotatably and slidably received in a vertical sleeve 81welded between a pair of right angled bracket sleeves 82, 82 slidablyengaged on the bars 74, 74.

As shown in FIGURE 2, the bracket member 77 comprises a clamping sleeveadjustably mounted on the vertical post 78 provided with a horizontalsleeve portion Which is clampingly engageable with the rod 79, so thatthe location of the vertical shaft, or fulcrum 80 may be adjustedhorizontally, as well as vertically.

Due to the pivotal and sliding connection between the fixed verticalshaft 80 and the bars 74, 74, the resultant path of movement of thevertical shaft 71 is governed by the path of movement of the shaft 60.Thus, since the shaft 60 moves in a rotating substantially closed-looppath, the shaft 71 likewise moves in a rotating substantiallyclosed-loop path controlled by the path of the shaft 60 and withparameters depending upon the relationship of the radial distancebetween shaft 60 and pivot shaft 80 and that between pivot shaft 80 andshaft 71. Thus, with the pivot shaft 89 in the leftward position ofFIGURE 14A, shaft 71 moves in laterally elongated substantiallyclosed-loop paths such as 71a or 7112 in FIGURE 14A. With pivot shaft 80in the intermediate position thereof shown in FIGURE 14B, shaft 71 movesin relatively nonelongated substantially closed-loop paths such as 171aor 171]; in FIGURE 1413. With pivot shaft 80 in the rightward positionthereof shown in FIGURE 14C, shaft 71 moves in a longitudinallyelongated substantially closed-loop path such as 271a or 2711) in FIGURE14C.

It will be noted that each blank 68 and 23 is provided with a similarsupporting disc 69 and 69 having bracket means for interchangeableconnection in the universal joint 70 so that the blanks may beinterchanged without the necessity of removing and recementing theirsupporting discs thereof.

The sleeve member 75 which comprises the bearing support for the members74, 74 is rotatably supported on the top flanges of the members 58, 58.Designated at 84 is a channel-shaped member provided with upper andlower pairs of spaced horizontally extending arms 85, 85 and 86, 86which slidably receive a vertical bearing sleeve member 87 which issupportingly connected to a sleeve member 88, rotatably receiving theshaft 60, by a turn buckle assembly 89. As shown in FIGURE 5, the sleeve88 is rotatably supported on the top edge of the sleeve 59.

Journaled in the sleeve 87 is a vertical shaft 90 to the top and bottomportions of which are journaled the respective pulleys 91 and 92,retaining collars 93 and 94- being secured on the shaft 9t) above andbelow the re spective pulleys 91 and 92, as shown in FIGURE 5. Thepulley 91 is drivingly coupled by a belt 95 to a substantially largerpulley 96 secured on the top portion of shaft 60. The pulley 92 isdrivingly coupled by a belt 97 to a pulley 98 which is secured on theupper portion of sleeve 59, immediately above the bearing sleeve 75. Thepulley 98 is slightly smaller than the upper pulley 96. The turn buckleassembly 89 is adjusted so that the pulleys 91 and 92 are urgedoutwardly with sufficient force to maintain substantial tension in thebelts 95 and 97, the outward horizontal force exerted on the sleeve 87creating said tension, and the forces in the belts 95 and 97 beingsubstantially balanced. The tension in the belts 95 and 97 acts tomaintain the shaft 90 vertical and also the balance of tensions includesa sufiicient supporting component to maintain the turn buckle assembly89 substantially horizontal and the bearing sleeve 37 substantiallyvertical.

Rigidly secured to the guide member 84 is an elongated supporting rod 99which extends parallel to the turn buckle assembly 89 and projectssufliciently to overlie the slot defined between the members 74, 74. Rod99 is rigidly secured to sleeve 88 by an arm 107. A vertical dependingrod member 106 is rigidly secured to the end of the elongated rod 99,said depending rod 100 extending between the arms 74, 74 so that theposition of the guide bracket member 84 is positively controlled and isheld fixed with respect to the arms 74, 74, since the rod 99 isconnected to the sleeve 88 which is coaxial with shaft 60, and thedepending rod 190 does not move in a longitudinal direction between themembers 74, 74. The depending rod element 100 thus constrains thebracket member 84 to remain in a fixed horizontal position with respectto the arms 74, 74, whereby the structure controlled by the bracketmember 84-, namely, the shaft 90, the pulleys 91, 92, the turn buckleassembly 89, and the parts associated with these elements are heldagainst horizontal movement with respect to the members 74, 74.

Secured on the shaft 6t) immediately below the pulley 96 and beingfreely rotatable with respect to the sleeve 88 is a relatively smallpulley 101 which is drivingly coupled by a belt 102 with the relativelylarge pulley 72 secured to the top end portion of shaft 71. Belt 102transmits torque from shaft 60 to shaft 71, so that the blank 68 isrotated simultaneously with the rotation of shaft 60, but at asubstantially slower speed. Thus, the blank 68 rotates around thevertical axis of shaft 71 and is simultaneously moved in the orbitalclosed-loop path above described. Thus, assuming counterclockwiserotation of the frame member 4-8, as viewed in FIGURES 6 and 7, theframe member 48 may be considered as having a starting position whereinit is aligned with the slot defined between the members '74, 74, underwhich conditions the blank 68 will be at its position of maximumdisplacement to the left, as viewed in FIGURES 2 and 6. Rotation of theframe 43 from the position of FIGURE 6 to the position of FIGURE 7causes the arm 65 to be swung around the shaft 66 from the position ofFIGURE 6, wherein it is directed upwardly and to the left, to theposition of FIGURE 7, wherein it is directed upwardly and to the right,the frame 48 having moved through an angle of approximately 135 in acounterclockwise direction. The action of the linkage elementsconnecting frame 49 to shaft 60 and the pivoted lever structure,comprising arms 74, 74, connecting sleeve to sleeve 73 causes therotating blank 68 to shift correspondingly from the position of FIGURE 6to the position of FIGURE 7. The blank 68, while rotating, moves througha rotating orbital path, shown for example in dotted view at 194 inFIGURE 7, providing a lapping cooperation between the rotating andorbitally moving upper blank 63 and the rotating lower blank 23.

Due to the continuous relative movement between the upper blank 68 andthe rotating bottom blank 23, the abrasive material, which is suppliedin a conventional manner so that it may be received between the bottomsurface of the upper blank 68 and the top surface of the lower blank 23,acts with maximum etficiency and uniforrnity of abrading action.

In accordance with the present invention, the member 23 may comprise aform or molding element and the member 68 may be a work piece whosesurface is to be ground according to the upper configuration of theforming member 23. However, in the preferred application of the presentinvention, both members 23 and 68 comprise blanks, with the top surfaceof the member 23 and the bottom surface of the member 68 beingsimultaneously ground and worked to a spherical contour. By suitablyadjusting the position of the vertical pivot shaft 89, as well as bysuitably adjusting the various elements of the driving linkageassociated with the transmission of driving force from the shaft 37 tothe shaft 60, the abrading force exerted between the upper member 68 andthe lower member 23 may be so applied as to effect zonal corrections ofdeviations for a desired type of curve and to eliminate unwanted zonaldeviations. Thus, initially, the surfaces between the members 23 and 63may be flat and horizontal. By suitably adjusting the position of thevertical pivot shaft E9, and by suitably adjusting the position of pivotshaft 66 relatively to the axis of shaft 37, the position of member 64on rod 65, and the position of member 62 on arm 61, the apparatus may beemployed to grind spherical surfaces of desired curvature between themembers 23 and 68. Thus, the top surface of the member 23 may be groundto a convex shape, Whereas the bottom surface of the member 68 may beground to a concave shape.

FIGURES 6 and 7 show why spherical surfaces are ground between themembers 68 and 23. It will be seen from FIGURES 6 and 7 that themovement of the upper member 68 takes place around an orbital axis pathwherein the upper member 63 generally projects laterally over theperiphery of the lower member 23 and rotates and oscillatescontinuously, so that it is generally off center with respect to thelower member 23, for example, moving from the starting position shown inFIGURE 6 in full line view and in FIGURE 7 in dotted view, to

the full line position shown in FIGURE 7, having moved in acounterclockwise direction, as viewed in FIGURES 6 and 7. As a result,the abrading action is heavier adjacent the periphery of the lowermember and in the center portion of the upper member than in the centerportion of the lower member and the periphery of the upper member, thedegree of difference depending upon the various adjustments abovementioned, since these adjustments determine the amount of throw of theupper member 68 relative to the bottom member 23, and upon thecoarseness of the abrasive used.

FIGURES 8, 9, 10, 11, 14A, 14B and 14C indicate clearly that the amountof displacement or throw, provided for the various linkage elements, andultimately applied to the shaft member 71, depends upon the length ofthe various link arms involved in the transmission of the driving torquefrom the shaft 37 to the lever elements 74, 74, and the degree ofexcursion of the shaft 71 is further dependent upon the position of thefulcrum shaft 80 in the slot defined between the members '74, 74.

FIGURE 12 illustrates the type of resultant surfaces which may beobtained by suitable adjustment of the above-mentioned members of themachine, and clearly illustrates how the blank 63 may move in itsorbital path around the lower form or blank 23 so that it constantlymoves orbitally along the periphery of the lower member 23 and extendslaterally over said periphery. Thus, FIGURE 12 shows the upper blank 68in a position corresponding to that shown in FIGURE 6, and also shows indotted view the position of the upper blank 68 corresponding to thatshown in FIGURE 7. It will be seen that the member 68 has been ground sothat its bottom surface 1% is spherically concave, whereas the topsurface of the lower blank 23, shown at 106, has been ground so that itis spherically convex.

The shaft 71 may be adjusted in a direction in a line including shaft 37and shaft 80. This adjustment does not accomplish the same thing as alateral adjustment of the shaft 89, since the path of the shaft 71 (suchas 271a in FIGURE 140) may be elongated and the speed of shaft 71 aroundits path is not constant. Since the path of shaft 71 (such as 271a) hasbilateral symmetry, lateral displacement of this path Will not providethe same relative motions between the upper and lower blanks as will adisplacement of this path along a direction in line with shafts 37 and849.

While a specific embodiment of an improved grinding and polishingmachine for optical elements, such as lenses, mirrors, or the like, hasbeen disclosed in the foregoing description, it will be understood thatvarious modifications within the spirit of the invention may occur tothose skilled in the art. Therefore, it is intended that no limitationsbe placed on the invention except as defined by the scope of theappended claims.

What is claimed is:

1. A grinding and polishing machine comprising a support, a horizontalbottom tray member, means to rotate said bottom tray member around avertical axis, means on said bottom tray member to support a lower blankfor coaxial rotation therewith, a horizontal arm, means slid ably andpivotally supporting said arm on said support with one end thereofextending over said bottom tray member, means on said one end torotatably support an upper blank adjacent and in overlying relation tosaid bottom tray member, means to rotate said last-named supportingmeans, and means driving the other end of said arm in a substantiallyclosed-loop path substantially in a horizontal plane.

2. A grinding and polishing machine comprising a support, a horizontalbottom tray member, means to rotate said bottom tray member around avertical axis, a central supporting block on said tray member, means onsaid central supporting block to support a lower blank for coaxialrotation therewith, a horizontal arm, means slidably and pivotallysupporting said arm on said support with' oneend thereof extending oversaid central supporting block, means on said one end to rotatablysupport an upper blank adjacent and in overlying relation to saidcentral supporting block, means to rotate said last-named supportingmeans, and means driving the other end of said arm in a substantiallyclosed-loop path substantially in a horizontal plane.

3. In a grinding and polishing machine comprising a support, ahorizontal bottom tray member, means to rotate said bottom tray memberaround a vertical axis on said support, means on said bottom tray memberto support a lower blank for coaxial rotation therewith, a horizontalarm, means slidably and pivotally supporting said arm on said supportwith one end thereof extending over said bottom tray member, means onsaid one end to rotatably support an upper blank adjacent and inoverlying relation to said bottom tray member, means to rotate saidlast-named supporting means, a vertical, horizontally elongated framerotatably mounted on said support, and means drivingly coupling saidframe to the other end of said arm and driving the other end of said armin a closed-loop path substantially in a horizontal plane.

4. In a grinding and polishing machine comprising a support, ahorizontal bottom tray member rotatably mounted on said support, meansto rotate said bottom tray member around a vertical axis, means on saidbottom tray member to support a lower blank for coaxial rotationtherewith, a horizontal arm means slidably and pivotally supporting saidarm on said support with one end thereof extending over said bottom traymember, means on said one end to rotatably support an upper blankadjacent and in overlying relation to said bottom tray member, means torotate said last-narned supporting means, a vertical driving shaftjournaled on said support, horizontally extending crank means secured tosaid shaft, means slidably connecting the other end of said arm to saidcrank means, and a linkage interconnecting said lastnamed means and saidcrank means and cooperating with said crank means to drive said otherend of the arm in a closed-loop path substantially in a horizontalplane.

5. A grinding and polishing machine comprising a support, a horizontaltray member rotatably mounted on said support, means to rotate saidbottom tray member around a vertical axis, means on said bottom traymemher to support a lower blank for coaxial rotation therewith, ahorizontal arm, means slidably and pivotally supporting said arm on saidsupport with one end thereof extending over said bottom tray member,means on said one end to rotatably support an upper blank adjacent andin overlying relation to said bottom tray member, means to rotate saidlast-named supporting means, a vertical driving shaft journaled on saidsupport, a vertical horizontally elongated crank frame secured on saidshaft, means slidably connecting the other end of said arm to said crankframe, and a pair of link members interconnecting said last-named meansand said crank frame and arranged to reciprocate said last-named meansalong said frame responsive to rotation of the shaft, whereby to drivesaid other end of the arm in a closed-loop path substantially in ahorizontal plane.

6. A grinding and polishing machine comprising a support, a horizontaltray member rotatably mounted on said support, means to rotate saidbottom tray member around a vertical axis, means on said bottom traymember to support a lower blank for coaxial rotation therewith, ahorizontal arm, means slidably and pivotally supporting said arm on saidsupport with one end thereof extending over said bottom tray member,means on said one end to rotatably support an upper blank adjacent andin overlying relation to said bottom tray member, a vertical drivingshaft journaled on said support, a vertical horizontally elongated crankframe secured on said shaft, means slidably connecting the other end ofsaid arm tosaid crank frame, a pair of link members interconnecting saidlast-named means and said crank frame and arranged to reciprocate saidlast-named means along said frame responsive to rotation of the shaft,whereby to drive said other end of the arm in a closed-loop pathsubstantially in a horizontal plane, vertical shaft means drivinglyconnected to one of said link members, and means drivingly coupling saidlast-named vertical shaft means to said lastnamed supporting means.

7. A grinding and polishing machine comprising a support, a horizontalbottom tray member rotatably mounted on said support, means to rotatesaid bottom tray member around a vertical axis, means on said bottomtray member to support a lower blank for coaxial rotation therewith, ahorizontal arm, means slidably and pivotally supporting said arm on saidsupport with one end thereof extending over said bottom tray member,means on said one end to rotatably support an upper blank adjacent andin overlying relation to said bottom tray member, a vertical drivingshaft journaled on said support, a vertical horizontally elongated crankframe secured on said shaft, means including a vertical sleeve slidablyconnecting the other end of said arm to said crank frame, a pair of linkmembers interconnecting said last-named means and said crank frame andarranged to reciprocate said last-named means along said frameresponsive to rotation of the shaft, whereby to drive said other end ofthe arm in a closed-loop path substantially in a horizontal plane,vertical shaft means journaled in said vertical sleeve and drivinglyconnected to one of said link members, and means drivingly coupling saidlast-named vertical shaft means to said 1ast-named supporting means.

8. A grinding and polishing machine comprising a support, a horizontalbottom tray member rotatably mounted on said support, means to rotatesaid bottom tray member, means on said bottom tray member to support alower blank for coaxial rotation therewith, a horizontal arm, verticalpivot means on said support, said arm being formed with longitudinalslot means slidably receiving said vertical pivot means, whereby the armslidably and pivotally engages said vertical pivot means, said pivotmeans being located so that one end of said arm overlies said bottomtray member, means on said one end to rotatably support an upper blank,adjacent and in overlying relation to said bottom tray member, meansrotating said last-named supporting means, a vertical driving shaft onsaid support, and means coupling said driving shaft to the other end ofsaid arm and driving said other end in a closed-loop path in ahorizontal plane.

9. A grinding and polishing machine comprising a support, a horizontalbottom tray member rotatably mounted on said support, means to rotatesaid bottom tray member, means on said bottom tray member to support alower blank for coaxial rotation therewith, a horizontal arm, verticalpivot means on said support, said arm being formed with longitudinalslot means slidably receiving said vertical pivot means, whereby the armslidably and pivotally engages said vertical pivot means, said pivotmeans being located so that one end of said arm overlies said bottomtray member, means on said one end to rotatably support an upper blankadjacent and in overlying relation to said bottom tray member, avertical driving shaft on said support, means coupling said drivingshaft to the other end of said arm and driving said other end in aclosedloop path in a horizontal plane, and means drivingly coupling saidvertical driving shaft to said means to support the upper blank.

10. A grinding and polishing machine comprising a sup port, a horizontalbottom tray member rotatably mounted on said support, means to rotatesaid bottom tray member, means on said bottom tray member to support alower blank for coaxial rotation therewith, a horizontal arm, verticalpivot means on said support, said arm being formed with longitudinalslot means slidably receiving said vertical pivot means, whereby the armslidably and pivotally engages said vertical pivot means, said pivotmeans being located so that one end of said arm overlies said bottomtray member, means on said one end to rotatably support an upper blankadjacent and in overlying relation to said bottom tray member, avertical driving shaft on said support, crank means interconnecting saidvertical driving shaft and the other end of said arm and moving saidother end of the arm in a horizontal plane in a closed-loop path aroundthe axis of said vertical driving shaft, vertical shaft means extendingrotatably through said other end of the arm and connected to said crankmeans, and means drivingly connecting said lastnamed vertical shaftmeans to said means to support the upper blank.

11. An optical grinding and polishing machine comprising a support, ahorizontal bottom tray member rotatably mounted on said support forrotation around a vertical axis, means to rotate said bottom traymember, upstanding pin means on the central portion of said bottom traymember defining an enclosure to receive a lower blank and to supportsame for coaxial rotation with said bottom tray member, a longitudinallyslotted horizontal arm, vertical pivot means on said support above andadjacent said bottom tray member, said pivot means engaging in the slotof said horizontal arm, whereby the arm is slidably and pivotallyengaged with said pivot means, with one end of said arm overlying thecentral portion of the tray member, vertical shaft means on said one endadapted to rotatably support an upper blank in overlying relation to alower blank in said enclosure, means rotating said vertical shaft means,a vertical driving shaft on said support, and means coupling saiddriving shaft to said other of the arm and being arranged to drive saidother end in a closed-loop path in a horizontal plane.

12. An optical grinding and polishing machine comprising a support, ahorizontal bottom tray member rotatably mounted on said support forrotation around a vertical axis, means to rotate said bottom traymember, upstanding pin means on the central portion of said bottom traymember defining an enclosure to receive a lower blank and to supportsame for coaxial rotation with said bottom tray member, a longitudinallyslotted horizontal arm, vertical pivot means on said support above andadjacent said bottom tray member, said pivot means engaging in the slotof said horizontal arm, whereby the arm is slidably and pivotallyengaged with said pivot means, with one end of said arm overlying thecentral portion of the tray member, vertical shaft means on said one endadapted to rotatably support an upper blank in overlying relation to alower blank in said enclosure, means rotating said vertical shaft means,a vertical driving shaft on said support, a vertical horizontallyelongated rectangular frame having its bottom portion secured on saiddriving shaft, means slidably and pivotally connecting the other end ofsaid arm to the top portion of said frame, and link meansinterconnecting said last-named means and. said bottom portion of theframe and being arranged to reciprocate said last-named means along saidframe top portion responsive to rotation of the driving shaft, wherebyto drive said other end of the arm in a closed-loop path in a horizontalplane.

13. An optical grinding and polishing machine comprising a support, ahorizontal bottom tray member rotatably mounted on said support forrotation around a vertical axis, means to rotate said bottom traymember, upstanding pin means on the central portion of said bottom traymember defining an enclosure to receive a lower blank and to supportsame for coaxial rotation with said bottom tray member, a longitudinallyslotted horizontal arm, vertical pivot means on said support above andadjacent said bottom tray member, said pivot means engaging in the slotof said horizontal arm, whereby the arm is slidably and pivotallyengaged with said pivot means, with one end of said arm overlying thecentral portion of the tray member, vertical shaft means on said one endadapted to rotatably support an upper blank in overlying relation to alower blank in said enclosure, a vertical driving shaft on said support,a vertical horizontally elongated rectangular frame having its bottomportion secured on said driving shaft, means including a vertical sleeveslidably and pivotally connecting the other end of said arm to the topportion of said frame, link means interconnecting said last-named meansand said bottom portion of the frame and being arranged to reciprocatesaid last-named means along said frame top portion responsive torotation of the driving shaft, whereby to drive said other end of thearm in a closed-loop path in a horizontal plane, a shaft jour- 10 71,577,137

naled in said sleeve and drivingly connected to said link means, andmeans drivingly connecting said last-named shaft to the vertical shaftmeans to rotatably support the upper blank.

References Cited in the file of this patent UNITED STATES PATENTS SteadJune 19, 1917 Maynard Mar. 16, 1926

1. A GRINDING AND POLISHING MACHINE COMPRISING A SUPPORT, A HORIZONTALBOTTOM TRAY MEMBER, MEANS TO ROTATE SAID BOTTOM TRAY MEMBER AROUND AVERTICAL AXIS, MEANS ON SAID BOTTOM TRAY MEMBER TO SUPPORT A LOWER BLANKFOR COAXIAL ROTATION THEREWITH, A HORIZONTAL ARM, MEANS SLIDABLY ANDPIVOTALLY SUPPORTING SAID ARM ON SAID SUPPORT WITH ONE END THEREOFEXTENDING OVER SAID BOTTOM TRAY MEMBER, MEANS ON SAID ONE END TOROTATABLY SUPPORT AN UPPER BLANK ADJACENT AND IN OVERLYING RELATION TOSAID BOTTOM TRAY MEMBER, MEANS TO ROTATE SAID LAST-NAMED SUPPORTINGMEANS, AND MEANS DRIVING THE OTHER END OF SAID ARM IN A SUBSTANTIALLYCLOSED-LOOP PATH SUBSTANTIALLY IN A HORIZONTAL PLANE.